IEMbase 0329: ALG1-related mannosyltransferase 1 deficiency
Scope
| Field | Value |
|---|---|
| IEMbase ID | 329 |
| Nosology | 18.1.07.01 |
| Gene | ALG1 |
| External IDs | OMIM:608540; ORPHA:79327 |
| Generated mapping | CANDIDATE to ALG12_Congenital_Disorder_of_Glycosylation.yaml |
| Candidate DisMech targets | No valid local ALG1-CDG target |
| Review date | 2026-07-07 |
IEMbase phenotype signal
IEMbase represents ALG1-CDG/CDG-Ik. Characteristic rows include epilepsy, facial dysmorphism, poor visual fixation, and strabismus. Additional clinical rows include axial hypotonia, cardiomyopathy, cerebellar hypoplasia, contractures, cortical atrophy on MRI, chronic diarrhea, fatal outcome, feeding difficulties, hypertelorism, large everted ears, microcephaly, nephrotic syndrome, psychomotor delay, scoliosis, small almond-shaped eyes, small mouth, thin lips, thrombocytopenia, turned-up nose, and wide nasal bridge.
The biochemical profile includes normal-to-increased transaminase, increased asialotransferrin and disialotransferrin, increased fibroblast lipid-linked GlcNAc2, type 1 sialotransferrin pattern, decreased tetrasialotransferrin, low-to-normal albumin, increased serum dolichol-linked GlcNAc2, and low-to-normal protein C. No treatment rows are present.
DisMech phenotype coverage
The generated ALG12-CDG candidate is a false positive. ALG1 and ALG12 are both type I CDG genes in lipid-linked oligosaccharide assembly, but they represent different enzymatic steps and different disease entities. Local ALG12-CDG coverage should not be reused for ALG1-CDG.
Existing local CDG resources provide family context only. ALG9 and MGAT2 files mention ALG1 in systematic CDG/nonimmune hydrops literature, but those mentions are not standalone disease coverage.
Concordance and completeness
Judgement: true local disease gap; reject the ALG12 candidate.
IEMbase highlights a severe multisystem ALG1-CDG profile with neurologic, ocular, facial, cardiac, renal, gastrointestinal, skeletal, and coagulation signals. The biochemical rows are especially useful because the lipid-linked and dolichol-linked GlcNAc2 signals distinguish the early ALG1 assembly block from later ALG12/ALG9 blocks.
Curation actions
- Add a standalone ALG1-CDG target before treating this record as mapped.
- Do not map this record to ALG12-CDG or ALG9-CDG based on broad type I CDG overlap.
- Preserve nephrotic syndrome, cardiomyopathy, cortical/cerebellar findings, thrombocytopenia, protein C, and GlcNAc2 lipid-linked/dolichol-linked rows as future-curation prompts.